System for Networking and Analyzing Geospatial Data, Human Infrastructure, and Natural Elements

ABSTRACT

A method and system for providing a recovery sequence for a network from a state of disruption to a state of partial or complete functionality are provided. The method and system can measure the response of a network to one or multiple hazards and can generate and compare the effectiveness of multiple recovery strategies in a quantitative and generalizable manner, providing a user with practical tools to implement an efficient restoration of the network.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 §119(e) of U.S. ProvisionalApplication No. 62/153,243 filed on Apr. 27, 2015, entitled “SoftwareSystem for Generating an Analyzing Quantitative Restoration and RecoveryStrategies and Scenarios for Man-Made and Natural Complex Networks”, thedisclosure of which is hereby incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention was developed with financial support from Grant No.14475876 from The National Science Foundation and from Grant No. 1029711from The National Science Foundation. The U.S. Government has certainrights in the invention.

BACKGROUND

Complex, large-scale networks exist in systems ranging fromtransportation to communications, water and power distribution, ecology,climate, biology and more. Complex large-scale networks include criticallifeline infrastructure networks, such as water distribution pipelines,power grids, railways, roadways, seaports, airports, andtelecommunication networks, including the Internet. These criticallifeline infrastructure networks are subject to threats from natural andhuman-made hazards, such as severe weather events, power outages,climate extremes, terrorism, and cybercrime. Aging infrastructures,connectivity of lifeline functions, competition for resources,urbanization and movement towards coastlines have increased pressures onthese critical networks.

The resilience of networks to various threats has been examined,particularly in the context of specific types of hazard andinfrastructure and using known fragility models or component-levelresource constraints. However, these studies have not provided anypractical methods or tools for recovering a network that has beendisrupted, particularly where component-specific information is notknown.

SUMMARY OF THE INVENTION

The invention relates to a method and system that provide practicaltools for recovery of networks from disruption. The method can be usedto measure the response of a network to one or multiple hazards as wellas to generate and compare the effectiveness of multiple restorationstrategies in a quantitative and generalizable manner. Optimal recoverystrategies can be different for different hazards, for differentcommunities within a network and for different measures of partialrecovery.

Other aspects of the method and system include the following:

1. A method for providing a recovery sequence for a network from a stateof disruption to a state of partial or complete functionality, thenetwork comprising a plurality of nodes interconnected by links, thenetwork subject to disruption that removes from the network one or morenodes, one or more links, or a combination of one or more nodes and oneor more links, wherein a disrupted node comprises a node through whichtraffic cannot flow and a functional node comprises a node through whichtraffic can flow, the method comprising:

providing a backend computing device comprising one or more processorsand memory, and a user interface in communication with the backendcomputing device;

storing, in a database in the memory, data comprising identities of thenodes and the links of the network, attributes of the nodes, andattributes of the links;

receiving user preference data from a user at the user interface, theuser preference data including a state of desired functionality, and oneor more of a type of hazard, severity of hazard, location of hazard,resilience budget, and cost of node or link repair;

receiving, at the backend computing device, an identification of aplurality of the nodes as disrupted nodes;

determining, by a scientific engine comprising instructions stored inthe memory for execution by the one or more processors, a priorityrecovery sequence by which disrupted nodes are to be restored to thestate of desired functionality; and

providing to the user interface a priority recovery sequence to restorethe network to the desired state of functionality.

2. The method of item 1, wherein storing data comprises one or more of:

(a) populating a network data object with the data comprising theidentities of the nodes and the links of the network, the attributes ofthe nodes, and the attributes of the links, and pushing the network dataobject to the database stored in the memory;

(b) augmenting or overriding the data in the network data object in thedatabase with a further data input by a user at the user interface; and

(c) querying node and link data to refresh the node and link data, andpushing an updated network data object to the database.

3. The method of item 2, wherein step (c) comprises querying the nodeand link data on a periodic schedule.4. The method of any of items 1-3, wherein identifying the nodes asdisrupted nodes comprises receiving an input from an external computingdevice, from sensors located at the nodes, or from the user interfacecomprising identities of disrupted nodes or links.5. The method of any of items 1-4, further comprising:

receiving from a sensor located at a disrupted node data indicating thatthe disrupted node has been restored to functionality;

updating, by the scientific engine, the priority recovery sequence; and

providing the updated priority recovery sequence to the user interface.

6. The method of any of items 1-5, wherein providing the priorityrecovery sequence to the user interface comprises transmitting agraphical display to the user interface comprising a graph illustratinga fraction of disrupted nodes vs. a state of critical functionality forone or a plurality of recovery sequences.7. The method of any of items 1-6, further comprising transmitting agraphical display to the user interface comprising a graph illustratinga fraction of disrupted nodes vs. a state of critical functionality fora variety of hazard scenarios.8. The method of any of items 1-7, further comprising providing to theuser interface one or more metrics comprising financial savings,prevented down time of the network, prevented temporal businessinterruption, prevented socioeconomic damage, prevented disease spread,mitigated transportation losses in terms of traffic volume not delayed,prevented downtime in power supply from a blackout or brownout,prevented Internet downtime, or prevented natural ecosystem losses thatresult from alternative proposed recovery sequences.9. The method of any of items 1-8, wherein the user interface isprovided on an external computing device.10. The method of any of items 1-9, wherein the step of determining apriority recovery sequence comprises:

determining, by the scientific engine, a giant component of the nodes,the giant component comprising a largest connected set of nodes; and

determining, by the scientific engine, an initial value of a state ofcritical functionality (SCF), the SCF ranging from 0 to 1 and comprisinga fragmented functionality (FF) divided by a total functionality (TF),wherein:

-   -   FF is a number of functional nodes in the giant component at a        determined time, and    -   TF is a total number of nodes in the giant component when the        network is fully functional; and

simulating, by the scientific engine, restoration of the disrupted nodesone by one to functionality until a desired value of SCF is obtained.

11. The method of item 10, wherein simulating restoration of a disruptednode comprises adding the disrupted node and the connections of thedisrupted node to its neighboring nodes back to the network.12. The method of any of items 10-11, wherein determining a priorityrecovery sequence comprises:(a) determining a first SCF value after disruption;(b) simulating restoration of one of the disrupted nodes to fullfunctionality;(c) calculating a number of functional nodes in the giant component;(d) determining a further SCF value; and(e) repeating steps (b) through (d) until a desired SCF value isreached.13. The method of item 12, wherein in step (e), the desired SCF value is1.14. The method of any of items 1-13, wherein the step of receiving aninput of a disruption further comprises identifying links between anydisrupted node and a neighboring node.15. The method of any of items 1-14, wherein determining a priorityrecovery sequence comprises determining multiple recovery sequences andcomparing the multiple recovery sequences to determine the priorityrecovery sequence.16. The method of any of items 1-15, wherein the determined recoverysequence comprises one or more of:

(a) a sequence in which a desired state of critical functionality (SCF)value can be achieved in a fastest time.

(b) a sequence in which a desired SCF value can be achieved with afewest number of steps.

(c) placing the disrupted nodes in order by degree, wherein degreecomprises a number of links to a node, and simulating restoration of thedisrupted nodes to functionality, in order from largest degree tosmallest degree, until a desired value of SCF is obtained;

(d) placing the disrupted nodes in order by clustering coefficient,wherein the clustering coefficient is proportional to a number of linksto nodes to which a disrupted node is linked, and simulating restorationof the disrupted nodes to functionality, in order from largestclustering coefficient to smallest clustering coefficient, until adesired value of SCF is obtained;

(e) placing the disrupted nodes in order of betweenness centrality,wherein the betweenness centrality is a measure of how frequent adisrupted node is a bridge between otherwise disconnected groups ofintra-linked nodes, and simulating restoration of the disrupted nodes tofunctionality, in order from largest betweenness centrality to smallestbetweenness centrality, until a desired value of SCF is obtained;

placing the disrupted nodes in order of closeness centrality, whereinthe closeness centrality is an inverse of a summation of a number ofnetwork steps between a node and other nodes, and simulating restorationof the disrupted nodes to functionality, in order from smallestcloseness centrality to largest closeness centrality, until a desiredvalue of SCF is obtained;

(g) placing the disrupted nodes in order of eigenvector centrality,wherein the eigenvector centrality is a sum of the centrality values ofeach node that is linked to a disrupted node, and simulating restorationof the disrupted nodes to functionality, in order from largesteigenvector centrality to smallest eigenvector centrality, until adesired value of SCF is obtained; and

(h) placing the disrupted nodes in a random order, and simulatingrestoration of the disrupted nodes to functionality in the random order,until a desired value of SCF is obtained.

17. The method of any of items 1-16, wherein node attributes include oneor more of:

(a) strength measured as a volume of originations or terminations at thenode or measured as a number of objects originating or terminating atthe node; and

(b) degree, the degree comprising a number of connections of one nodewith other nodes.

18. A method of recovering a network from a state of disruption to astate of partial or complete functionality, the network comprising aplurality of nodes interconnected by links, the network subject todisruption that removes from the network one or more nodes, one or morelinks, or a combination of one or more nodes and one or more links,wherein a disrupted node comprises a node through which traffic cannotflow and a functional node comprises a node through which traffic canflow, the method comprising:

performing the method of any of items 1-17; and

implementing the recovery sequence.

19. The method of item 18, wherein implementing the recovery sequencecomprises restoring at least a first disrupted node or a first disruptedlink to functionality according to the recovery sequence.20. The method of any of items 18-19, wherein the network comprises atransportation network, an energy network, an ecological network, acommunication network, an Internet network, a water supply network, afinancial network, a social network, a climate and weather network, ageopolitical network, or a disease network.21. The method of any of items 18-19, wherein the network comprises atelecommunication network or an Internet network.22. The method of any of items 18-21, wherein the network is connectedto a further network, and the network and the further network arerecovered as a composite network.23. The method of any of items 18-22, wherein traffic flowing through anode comprises data, objects, people, or non-human animals.24. A system for determining a recovery sequence for a network from astate of disruption to a state of partial or complete functionality, thenetwork comprising a plurality of nodes interconnected by links, thenetwork subject to disruption that removes from the network one or morenodes, one or more links, or a combination of one or more nodes and oneor more links, wherein a disrupted node comprises a node through whichtraffic cannot flow and a functional node comprises a node through whichtraffic can flow, the system comprising:

a backend computing device comprising one or more processors and memory,a user interface in communication with the backend computing device, andmachine-readable instructions stored in the memory that, upon executionby the one or more processors cause the system to carry out operationscomprising the method of any if items 1-23.

25. A non-transitory computer readable medium with computer executableinstructions stored thereon executed by a processor to perform themethod of any of items 1-23.26. A method for providing a recovery sequence for a network from astate of disruption to a state of partial or complete functionality, thenetwork comprising a plurality of nodes interconnected by links, thenetwork subject to disruption that removes from the network one or morenodes, one or more links, or a combination of one or more nodes and oneor more links, wherein a disrupted node comprises a node through whichtraffic cannot flow and a functional node comprises a node through whichtraffic can flow, the method comprising:

storing, in memory, data comprising identities of the nodes and thelinks of the network, attributes of the nodes, and attributes of thelinks;

receiving, at one or more processors in communication with the memory,user preference data from a user, the user preference data including astate of desired functionality, and one or more of a type of hazard,severity of hazard, location of hazard, resilience budget, and cost ofnode or link repair;

receiving, at the one or more processors, an identification of aplurality of the nodes as disrupted nodes;

determining, by instructions stored in the memory for execution by theone or more processors, a priority recovery sequence by which disruptednodes are to be restored to the state of desired functionality; and

providing to the user, by the one or more processors, a priorityrecovery sequence to restore the network to the desired state offunctionality.

27. The method of item 26, wherein storing data comprises one or moreof:

(a) populating a network data object with the data comprising theidentities of the nodes and the links of the network, the attributes ofthe nodes, and the attributes of the links, and pushing the network dataobject to the database stored in the memory;

(b) augmenting or overriding the data in the network data object in thedatabase with a further data input by a user at the user interface; and

(c) querying node and link data to refresh the node and link data, andpushing an updated network data object to the database.

28. The method of item 27, wherein step (c) comprises querying the nodeand link data on a periodic schedule.29. The method of any of items 26-28, wherein identifying the nodes asdisrupted nodes comprises receiving an input from an external computingdevice, from sensors located at the nodes, or from the user interfacecomprising identities of disrupted nodes or links.30. The method of any of items 26-29, further comprising:

receiving from a sensor located at a disrupted node data indicating thatthe disrupted node has been restored to functionality;

updating, by the scientific engine, the priority recovery sequence; and

providing the updated priority recovery sequence to the user.

31. The method of any of items 26-30, wherein providing the priorityrecovery sequence to the user comprises transmitting a graphical displayto a user interface comprising a graph illustrating a fraction ofdisrupted nodes vs. a state of critical functionality for one or aplurality of recovery sequences.32. The method of any of items 26-31, further comprising transmitting agraphical display to a user interface comprising a graph illustrating afraction of disrupted nodes vs. a state of critical functionality for avariety of hazard scenarios.33. The method of any of items 26-32, further comprising providing tothe user one or more metrics comprising financial savings, preventeddown time of the network, prevented temporal business interruption,prevented socioeconomic damage, prevented disease spread, mitigatedtransportation losses in terms of traffic volume not delayed, preventeddowntime in power supply from a blackout or brownout, prevented Internetdowntime, or prevented natural ecosystem losses that result fromalternative proposed recovery sequences.34. The method of any of items 26-33, further comprising providing auser interface on an external computing device.35. The method of any of items 26-34, wherein the step of determining apriority recovery sequence comprises:

determining a giant component of the nodes, the giant componentcomprising a largest connected set of nodes; and

determining an initial value of a state of critical functionality (SCF),the SCF ranging from 0 to 1 and comprising a fragmented functionality(FF) divided by a total functionality (TF), wherein:

-   -   FF is a number of functional nodes in the giant component at a        determined time, and    -   TF is a total number of nodes in the giant component when the        network is fully functional; and

simulating restoration of the disrupted nodes one by one tofunctionality until a desired value of SCF is obtained.

36. The method of item 35, wherein simulating restoration of a disruptednode comprises adding the disrupted node and the connections of thedisrupted node to its neighboring nodes back to the network.37. The method of item 35-36, wherein determining a priority recoverysequence comprises:(a) determining a first SCF value after disruption;(b) simulating restoration of one of the disrupted nodes to fullfunctionality;(c) calculating a number of functional nodes in the giant component;(d) determining a further SCF value; and(e) repeating steps (b) through (d) until a desired SCF value isreached.38. The method of item 37, wherein in step (e), the desired SCF value is1.39. The method of any of items 26-38, wherein the step of receiving aninput of a disruption further comprises identifying links between anydisrupted node and a neighboring node.40. The method of any of items 26-39, wherein determining a priorityrecovery sequence comprises determining multiple recovery sequences andcomparing the multiple recovery sequences to determine the priorityrecovery sequence.41. The method of any of items 26-40, wherein the determined recoverysequence comprises one or more of:

(a) a sequence in which a desired state of critical functionality (SCF)value can be achieved in a fastest time.

(b) a sequence in which a desired SCF value can be achieved with afewest number of steps.

(c) placing the disrupted nodes in order by degree, wherein degreecomprises a number of links to a node, and simulating restoration of thedisrupted nodes to functionality, in order from largest degree tosmallest degree, until a desired value of SCF is obtained;

(d) placing the disrupted nodes in order by clustering coefficient,wherein the clustering coefficient is proportional to a number of linksto nodes to which a disrupted node is linked, and simulating restorationof the disrupted nodes to functionality, in order from largestclustering coefficient to smallest clustering coefficient, until adesired value of SCF is obtained;

(e) placing the disrupted nodes in order of betweenness centrality,wherein the betweenness centrality is a measure of how frequent adisrupted node is a bridge between otherwise disconnected groups ofintra-linked nodes, and simulating restoration of the disrupted nodes tofunctionality, in order from largest betweenness centrality to smallestbetweenness centrality, until a desired value of SCF is obtained;

(f) placing the disrupted nodes in order of closeness centrality,wherein the closeness centrality is an inverse of a summation of anumber of network steps between a node and other nodes, and simulatingrestoration of the disrupted nodes to functionality, in order fromsmallest closeness centrality to largest closeness centrality, until adesired value of SCF is obtained;

(g) placing the disrupted nodes in order of eigenvector centrality,wherein the eigenvector centrality is a sum of the centrality values ofeach node that is linked to a disrupted node, and simulating restorationof the disrupted nodes to functionality, in order from largesteigenvector centrality to smallest eigenvector centrality, until adesired value of SCF is obtained; and

(h) placing the disrupted nodes in a random order, and simulatingrestoration of the disrupted nodes to functionality in the random order,until a desired value of SCF is obtained.

42. The method of any of items 26-41, wherein node attributes includeone or more of:

(a) strength measured as a volume of originations or terminations at thenode or measured as a number of objects originating or terminating atthe node; and

(b) degree, the degree comprising a number of connections of one nodewith other nodes.

43. The method of any of items 26-42, wherein at least a portion of theone or more processors and the memory are provided in a backendcomputing device and a user interface is provided in communication withthe backend computing device.44. A method of recovering a network from a state of disruption to astate of partial or complete functionality, the network comprising aplurality of nodes interconnected by links, the network subject todisruption that removes from the network one or more nodes, one or morelinks, or a combination of one or more nodes and one or more links,wherein a disrupted node comprises a node through which traffic cannotflow and a functional node comprises a node through which traffic canflow, the method comprising:

performing the method of any of items 26-43; and

implementing the recovery sequence.

45. The method of item 44, wherein implementing the recovery sequencecomprises restoring at least a first disrupted node or a first disruptedlink to functionality according to the recovery sequence.46. The method of any of items 44-45, wherein the network comprises atransportation network, an energy network, an ecological network, acommunication network, an Internet network, a water supply network, afinancial network, a social network, a climate and weather network, ageopolitical network, or a disease network.47. The method of any of items 44-45, wherein the network comprises atelecommunication network or an Internet network.48. The method of any of items 44-47, wherein the network is connectedto a further network, and the network and the further network arerecovered as a composite network.49. The method of any of items 46-48, wherein traffic flowing through anode comprises data, objects, people, or non-human animals.50. A system for determining a recovery sequence for a network from astate of disruption to a state of partial or complete functionality, thenetwork comprising a plurality of nodes interconnected by links, thenetwork subject to disruption that removes from the network one or morenodes, one or more links, or a combination of one or more nodes and oneor more links, wherein a disrupted node comprises a node through whichtraffic cannot flow and a functional node comprises a node through whichtraffic can flow, the system comprising:

a backend computing device comprising one or more processors and memory,a user interface in communication with the backend computing device, andmachine-readable instructions stored in the memory that, upon executionby the one or more processors cause the system to carry out operationscomprising the method of any if items 26-49.

51. A non-transitory computer readable medium with computer executableinstructions stored thereon executed by a processor to perform themethod of any of items 26-49.

DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a schematic block diagram of an embodiment of a method andsystem for planning for recovery of a network;

FIG. 2 is an illustration of an embodiment of a graphical user interfaceof the method and system;

FIG. 3 is a schematic block diagram of an embodiment of a method andsystem for determining a real-time or near real-time optimal recoverystrategy in response to a hazard;

FIG. 4 is a schematic block diagram of an embodiment of a scientificengine for determining one or more recovery strategies of a network;

FIG. 5 illustrates a simplified example of a disruption process followedby a recovery process;

FIG. 6 is a topological diagram of the Indian Railway Network;

FIG. 7 is an embodiment of a graphical representation of determinedrecovery strategies; and

FIG. 8 is a graphical representation of a quantification of revenuerecovered under various recovery sequences.

DETAILED DESCRIPTION OF THE INVENTION

This application incorporates by reference the entire disclosure of U.S.Provisional Application No. 62/153,243 filed on Apr. 27, 2015, entitled“Software System for Generating an Analyzing Quantitative Restorationand Recovery Strategies and Scenarios for Man-Made and Natural ComplexNetworks”.

The invention relates to a method and system that provides ageneralizable solution for recovery of a real world lifeline networkfrom a state of disruption to a desired state of partial or completefunctionality. A network can be considered as a plurality of nodesinterconnected by links. The network is subject to disruption thatremoves from the network one or more nodes, one or more links, or acombination of one or more nodes and one or more links. A disrupted nodeis a node through which traffic cannot flow, and a functional node is anode through which traffic can flow.

The method and system provide a recovery sequence for a network from astate of disruption to a state of partial or complete functionality byemploying a metric, termed herein a State of Critical Functionality(SCF), to measure the network at any state of functionality. The SCFranges from 0 to 1, where at 0 the network is completely dysfunctional,and at 1 the network is at full functionality. An SCF between 0 and 1means that the network is operating at a state of partial functionality.The recovery solution is a time or step-based process wherein eachcomponent is restored one by one until the SCF=1 or any desired value ofpartial functionality. A component of a network can be a node or a linkbetween nodes.

Multiple proposed recovery sequences can be generated, where a recoverysequence is the proposed order in which components can be restored tofunctionality. Recovery sequences can be proposed using both intuitiveand more sophisticated metrics, including but not limited to: attributessuch as number of connections a component has and volume of data thatpasses through a component, and centrality measures for a givenconnection that quantifies its importance to data flowing through thenetwork.

Multiple generated recovery sequences can be compared to each other. Insome embodiments, an optimal recovery sequence for any desired SCF valueis, all else held equal, the recovery sequence that achieves the desiredSCF value fastest or with the fewest number of steps.

In some embodiments, a statistical significance testing routine can beincluded, in which many randomly generated recovery sequences aredetermined. In some embodiments, a proposed recovery sequence is said tobe more effective if it achieves a desired SCF faster than a majority(e.g., ≧95%) of randomly suggested sequences.

In some embodiments, recovery sequences can be generated for multipleinterconnected networks provided it is known how those networks areconnected to each other. For example, one network can be a power gridand a further network can be a transportation system. If the power gridwere disrupted, the transportation system could be disrupted as well.Concomitantly, recovery of the power grip could result in recovery ofthe transportation system. In some embodiments, recovery sequences canbe generated for communities within a network.

In some embodiments, the method and system can be implemented to provideproactive resilience planning, in terms of ensuring the most importantcomponents of a system are sufficiently resilient and/or to conceiveeffective recovery in the event that a network might be completely orpartially disrupted.

In some embodiments, the method and system can be implemented as a realor near-real time monitoring and decision support device, where in theevent of a disruption the method can suggest recovery priorities, forexample, when sensors indicate that one or more components of thelifeline network have been disrupted.

In some embodiments, the network resilience framework can consider linkdamage or removal and resource mobilization strategies, as well as theconsideration of dynamic network flow properties, including time varyingnetwork attributes and real time data ingestion.

In some embodiments, various metrics can be provided to quantify gainsfrom implementing one or each of the recovery sequences. Suchquantifiable metrics can be based on measurements of efficiency,performance, financial analyses, and the like. Examples can include,without limitation, financial savings, prevented down time of thenetwork, prevented business interruption in financial and time terms,prevented socioeconomic damage, prevented disease spread, mitigatedtransportation losses in terms of traffic volume not delayed, preventeddowntime in power supply from a blackout or brownout, prevented Internetdowntime, prevented criminal activity, and/or prevented naturalecosystem losses that result from alternative proposed recoverysequences.

Anticipatory analysis can help stakeholders design systematic recoveryand anti-fragility strategies for lifeline critical networks, includingtransportation, water and wastewater, power and fuels, andcommunications systems. In addition to engineered systems such aslifeline critical networks, the approach can be generalized to naturalsystems such as ecological networks subjected to perturbations.

Lifeline networks can either exist more literally and physically or beimposed via data analysis on many complex systems. Examples include thefollowing:

Energy systems: Nodes can be power plants, substations, and buildingsthat consume energy, and links can be the transmission and distributionlines that connect them.

Transportation systems: Nodes can be origins/destinations and links canbe roads, flight paths, railway lines, and water channels that connectthem. Nodes can also be stopping points between origins anddestinations.

Ecological systems: Nodes can be species, and links can be dependenciesbetween species, including, for example, predator/prey or symbioticrelationships.

Social networks: Nodes can be people or organizations of people, andlinks can be relationships or geographical connections between them.Alternatively, in a digital space (e.g., Twitter), links can beexplicitly labeled connections.

Communications systems: Nodes can be communications devices, and linkscan be inferred by data demonstrating that devices have communicatedwith each other. Links can also be physical infrastructure, such as, forexample, cell phone towers that can be connected to mobile devices.

Internet networks: Nodes can be servers, data centers, and/or devices(computers) connected to servers, and links can be connections betweenthem.

Climate and weather systems: Nodes can be points in space, and links canbe imposed by calculating correlations between weather patterns amongthose points in space.

Disease systems: Nodes can be infected organisms (people, plants,animals), and links can be the inferred connection where diseasesspread.

Water supply systems: Nodes can be consumption points (residences,industrial and commercial properties), water resources engineeringinfrastructure (water treatment facilities, desalination plants, dams,turbines, etc.), and natural components (ponds, lakes, rivers, aquifers,oceans). Links can be connections between them (water distribution,natural connection points).

Traffic flowing through networks can include data, physical objects,people, and non-human animals.

It will be appreciated that the method and system can be used for othertypes of networks. In addition, the technology can be applied to two ormore networks that are interconnected (e.g., an electric grid thatpowers a communication network as well as a railway network and anInternet network). Any of these networks could be hierarchical or nestedas well. For example, a transportation network could be comprised of asubway system, where each node is a subway station. Each of those subwaystations could be a network itself, dependent with multiplesub-components (nodes) that are linked.

Accordingly, the system and method provide a quantitative methodologyfor recovery of any real world lifeline network and can be generalizedto any network or system. The SCF metric, which uses the “giantcomponent,” is a relative measure that can be adapted to any lifelinenetwork or complex system. Also, the present system and method providethe generic ability to compare the effectiveness of multiple recoverystrategies or sequences for any real lifeline networks under disruption.

In some embodiments, a method and system for providing a recoverysequence for a network can be implemented as software- andhardware-based tools using a backend computing device 20 incommunication with a user interface 40, described further below. Adatabase 30 is provided to store node and link data related to a networkof interest. A priority recovery sequence can be generated by ascientific engine 50 in communication with the database and the userinterface.

FIG. 1 shows an embodiment of a system 10 in a “planning”/“scenarioanalysis” form, in which a complex network can also be, but is notnecessarily, monitored in real time. (Real time monitoring will bediscussed further below in conjunction with FIG. 3.) In FIG. 1 (and FIG.3), boxes are digital objects and arrows with associated text areactions, which can be either automated, computer-driven actions oruser-modulated actions. A digital object can contain content, such asdata elements and attributes of the data elements as well as attributesof the digital object itself. Each data object can be assigned anidentifier for access from any system for requesting content, adding ormodifying content, interaction between data objects, and the like. Adigital object architecture can allow ease of access and movement of thedigital objects among various computing systems and computer networks.

Referring to FIG. 1, one digital object 22 contains public or privategeospatial locational node data, and can also optionally describe otherattributes of the node. Geospatial data can include, for example,latitude, longitude, and height above sea level. As a further example,for an airline network in which a node is an airport, a node attributecan be annual air traffic volume that goes to and from the airport.Another digital object 24 contains data that describes the geospatialand/or temporal connections or links between nodes, either just the factthat they are connected or, optionally and additionally, attributes thatquantify the nature of those connections. For example, for an airlinenetwork, a link attribute can be a volume of flights between twoairports. For both objects 22 and 24, to obtain this node and link data,the computing device can query external public or private datarepositories, either once or on an automated, periodic schedule. In thelatter automated case, code can be provided that queries the node andlink data on a timer, refreshing the status of the node and link data.Those queries can populate a network data object 26; that data objecthosts all of the nodes and attributes, the links (between pairwise setsof nodes) and the space and potentially time attributes of the network.Any time the network data object is refreshed via those queries, a codecan push that updated network data object as a snapshot to a back enddatabase 28, which can reside on a backend or database server.

Node attributes can include, for example and without limitation,strength measured as a volume of originations or terminations at thenode or measured as a number of objects originating or terminating atthe node; a financial value associated with a node in terms of the costof repairing, recovering, or replacing that node; a financial valueassociated with a node in terms of business interruption costs relatedto that node being out of service; geospatial information, such aslatitude, longitude, and height above sea level; a quantifiable socialcost or variable associated with that node (e.g., if a node is aneighborhood, that node might be associated with a poverty rate, anemployment rate, and/or quantification of access to social servicesand/or alternative transportation; data about civil infrastructure(roads, bridges, tunnels, water and power distribution systems, and thelike) associated with the node; and natural environment data associatedwith the node. Link attributes can similarly include, withoutlimitation, strength measured as a volume of traffic measured as anumber of objects along or through the link; a financial valueassociated with a link in terms of the cost of repairing, recovering, orreplacing that link; a financial value associated with a link in termsof business interruption costs related to that link being out ofservice; geospatial information, such as latitude, longitude, and heightabove sea level; a quantifiable social cost or variable associated withthat link (e.g., if a link is in a neighborhood, that link might beassociated with a poverty rate, an employment rate, and/orquantification of access to social services and/or alternativetransportation; data about civil infrastructure (roads, bridges,tunnels, water and power distribution systems, and the like) associatedwith the link; and natural environment data associated with the link.Attributes of both nodes and links can be accorded a weight, such thatcertain attributes can have a greater impact on the determined recoverysequences.

The user interface provides a digital object 42, which is provided atthe front end 40 of the system that the user sees. The digital object 42can be loaded into, for example, a web browser or a mobile applicationinterface. The user sees a geospatial network visualization augmented bydefault resilience outputs, described further below. The front end canallow for several user-driven specifications. For example, the user caninput node or link attributes and a weighting for each attribute. Insome embodiments, a digital object 44 contains parameters that a usercan specify when doing resilience planning and scenario analysis. Theseparameters can include the type and severity of hazard that could impactthe system. For example, a winter storm that hits an airport in Bostoncould cause delays that cascade to airports far away, and the user couldspecify the location of that hazard as well as, for example, the numberof inches of snow. Additionally, the user could input a resiliencebudget, either in terms of long term planning, as hazard response, orboth, and the cost of taking specific measures such as repairing onenode or link in the network. Digital object 46 is a feature that canallow a user to upload data in a specific, definitive form that caneither override properties of the network data object stored in thedatabase 30 or augment that data in the database. For example, in anairline network, a user could upload data that estimates the cost ofrepairing a “node” (an airport) and factor that into the restorationanalysis. Digital object 48 can allow a user to export the data from ananalysis to a local machine or server.

A digital object 52 can combine user specified inputs (data andparameters) with the backend digital object 28 to produce a data object54 that contains a resilience planning insight. More particularly, acore scientific engine 50 analyzes multiple methods of hazard responseand hazard recovery to find an optimal way to bring the system back to(user specified) partial or full functionality. The methods used withinobject 52 can consider a variety of network science metrics, includingthose related to degree and centrality, as well as intuitive metricslike node and link volume and also metrics specified by the user (suchas cost to repair any link or node), and any attribute weightings tofind an optimal recovery strategy conditional on all of those inputs.That strategy can be provided to the user interface 42. For example, thestrategy can be translated into and displayed as a set of graphics. FIG.2 illustrates an embodiment of a graphic, described further below. Thedigital object 48 can be provided to allow the user to export the datathat quantifies that optimal strategy to a local computer or server.

The engine 50 can also provide to the user interface 42 one or moremetrics to quantify gains or advantages from implementing one or each ofthe recovery sequences. Such quantifiable metrics can include, withoutlimitation, financial savings, prevented down time of the network,prevented temporal business interruption, prevented socioeconomicdamage, prevented disease spread, mitigated transportation losses interms of traffic volume not delayed, prevented downtime in power supplyfrom a blackout or brownout, prevented Internet downtime, preventedcriminal activity, and/or prevented natural ecosystem losses that resultfrom alternative proposed recovery sequences.

FIG. 2 is an exemplary (but not exhaustive) look at how the user caninteract with the method and system (i.e., digital objects 42, 44, 46,48 in FIG. 1). User input can be received through any suitable graphicaluser interface mechanism, such as text input boxes, drop down menuselections, buttons, sliders, and the like. For example, in someembodiments the interface can be configured to allow a user to choose asystem 104 that is pre-configured on the back end (i.e., in object 28from FIG. 1), to allocate a resilience budget 106, to specify apercentage of network recovery 108 (0% to 100%), and to select a hazardto analyze 110. In one example case using the Indian Railway Network asthe network, illustrated on a map 102, the user may have selected“Tropical Cyclone”, which by default might impact a region in thesoutheastern coast. The user can interact with the map, indicated at112, and select the region impacted by the hazard. The user can also adda secondary hazard attribute 114 (which would be constrained by thesystem dynamically after a user selects a type of hazard). The user canalso add further data 116. The system can prompt the user to add thedata in a specific form that will augment the network data stored in theback end database. User-added data could be, for example, costsestimated to repair each node or link (for example, an amount specificto railway stations, or an amount per specific train tracks betweenstations). Once a user has selected all of these configurations, theuser can update the analysis 118, by which the scientific engine wouldredetermine the recovery sequence(s). The “Hazard response” and “Hazardrecovery” graphics 122, 124 would be updated, and a new overlay on themap showing the system of interest post-hazard would be presented. Insome embodiments, a user can export that data from an analysis to alocal computer or server 126. The top right of FIG. 2 shows an examplein which a particular user is logged in at 128 and from a particularorganization, along with a logout button. The system can include an FAQor Help button 132 that can be searched (here shown to the left of thelogin options). An ability to interact with a system administrator toadd a new network 134 (e.g., in this case the user might want to add anew network to analyze, like the Indian power grid) can be provided.

FIG. 2 illustrates one exemplary manifestation of the method and systemand how it could look to a user, specifically in a web browser on alaptop or PC. It will be appreciated that the features of the user inputand interaction with the back end could vary from this depiction. Also,a different manifestation could be displayed in a mobile (phone ortablet) app, which can be substantively similar but optimized forviewing on the mobile app.

FIG. 3 illustrates an embodiment of the method and system that can beused as a near-real time or real time decision support tool for managinga network in any state of functionality. This embodiment can help amanager take actions to support network-wide resilience at any givenstate. FIG. 3 can differ from FIG. 1 within objects 22, 24, 26. Ratherthan an occasional external query, codes can be provided to queryexternal remote sensors at each node and link of the network to quantifytheir status. That status is converted to a current network data object26′ and then stored retrospectively in the backend database 30′. Thisembodiment is useful where the total network is well defined and themethod and system can be used for efficient network-wide real timehazard response and recovery. In light of that, user-specifiable optionscan be reduced or eliminated. Instead, if the status of one or moresensors changes, this change can inform a network-wide, optimal recoverystrategy, which can provide an alert and an update of the strategies tothe user interface 40′. In some embodiments, if a local user that is acomponent of a larger network needs to take action based on the optimalstrategy, the local user can receive an alert, potentially with specificrecommended actions, which are created in a network data object 54′,determined from strategies computed in the scientific engine 50′, andconveyed through user interface 42′, 40′. In some embodiments, acentralized decision maker can use the planning engine shown in FIG. 1to build the reactive module shown in FIG. 3. The user interface forthis reactive module can be similar to that shown in FIG. 2, withoutmany or any customization options.

The core scientific engine 50, 50′, shown in FIGS. 1 and 3, is describedwith more particularity by reference to FIG. 4. A network data object 60captures the system of interest at its full State of CriticalFunctionality, a metric that ranges from 0-1. At Full Functionality(FF), SCF=1. SCF can be computed by evaluating the currently largestcluster, or largest connected set of nodes in the network, (PF=PartialFunctionality) divided by the largest cluster at FF. Thus, SCF=PF/FF,ranging between 0 and 1. When the network is at full functionality, thatis the special case where PF=FF and so SCF=1. The SCF quantifies thesystem's ability to perform at full functionality and provides ameasuring stick to quantify and compare any suboptimal state of partialfunctionality. Given a hazard 62 and potentially user specifications(64, see also FIGS. 1-2), then data object 66 captures the post-hazarddescription of the network, and importantly its SCF. Its SCF is anindicator of the current, post-hazard “health,” or relativefunctionality, of the network. Given the post-hazard network data indata object 66, a set of recovery strategies 68 can be proposed. Thoserecovery strategies are based on computing a variety of metrics overeach node and/or link of the network, which can include but may not belimited to: degree (the number of connections any node has), centrality(the degree to which a node serves as a bridge between other nodes), andvolume of traffic that passes through a node. The alternative strategiesquickly analyze recovery strategies that use those metrics as a way toprioritize the repair of those nodes or links. Subsequently, in object72, the conditional partial and/or full rates of recovery under eachproposed strategy are evaluated, including under any potential usergiven constraints. For example, if a user needs or wants to achieve a50% system functionality, or SCF=0.5, the system can evaluate, accordingto different metrics, which recovery strategy is the fastest and leastexpensive node-prioritization scheme to get the network to SCF=0.5. Theoptimal recovery strategy from 72 can be captured in object 74 and canbe displayed to a user. Similarly, a planning module, object 76, can beprovided in which a user can evaluate the optimal prioritization ofnodes that should be enhanced to ensure future resilience underscenarios of plausible future hazards. Object 76 can use SCF as themetric for measuring the effectiveness of any such adaptation strategy.The difference between objects 74 and 76 lies within the goals of theworkflow: in 74 a user is trying to analyze the system as it currentlyis to quantify the best strategy. In 76 the user is trying to improvethe system to ensure optimal response to a future plausible hazard.

More particularly, the scientific engine utilizes a metric termed hereinthe State of Critical Functionality (SCF) to measure the functionalityof the system. The engine also utilizes the largest connected set(sometimes called the “giant component”) of nodes in the network. (Forexample, in a railway network, that would mean that a person couldtravel from any station i to any other station j by at least one path,perhaps with stops at interim stations.) Total Functionality (TF) is thenumber of nodes in the giant component when the network is completelyfunctional. For example, for a railway network, the giant componentcould be the total number of connected railway stations. FragmentedFunctionality (FE) is the number of nodes in the largest connected setat any given step, wherein one or more nodes are incapacitated bydisruptions. The State of Critical Functionality (SCF) can be thendefined as:

SCF=FF/TF.

Thus, SCF is effectively a measurement of critical functionality at anystep normalized between 0 and 1.

In operation to identify a prioritization sequence, the SCF is computedat the initial post-hazard state of the network. The prioritizationsequence is the order in which nodes should regain their fullfunctionality starting from the initial post-hazard state. For example,restoring the node A to full functionality requires restoring all edgesconnected to the node and partially activating the nodes which are onestep from node A. Nodes that are partially activated may not have fullfunctionality, since for these nodes, only the edges that directly leadto fully functional nodes are recovered. This sequence can be generatedrandomly, through intuitive, common sense metrics, or through otherstatistical or network science metrics.

Given a sequence, iteratively, until SCF=1:

-   -   a. The next node in the prioritization sequence is restored to        full functionality, re-establishing the traffic flow between        this node and the nodes to which it is connected. This grows the        giant component.    -   b. FF is recalculated.    -   c. SCF is recalculated.

The determination of a recovery sequence is described with moreparticularity as follows:

-   -   (1) Set SCF=1    -   (2) Set TF=total number of connected nodes in current network        (where SCF=1)    -   (3) Remove nodes X_(P) from X, where X represents all nodes and        P represents the subset of nodes impacted by a hypothetical        disruption. Removing nodes X_(P) also removes the connections        between any node within X_(P) and any other node.    -   (4) Multiple recovery prioritization sequences are identified.        The following are examples of some sequence-generating        functions. It will be appreciated that other sequence-generation        functions can be used.        -   a. Degree, k, where degree is defined as the number of            connections a node has. This sequence is in descending order            of degree.        -   b. Clustering coefficient of node i:

CC _(i)=2*E _(i)/(k _(i)*(k _(i)−1),

-   -   -   -   where E_(i) is the number of links that exist between                the k_(i) nodes that X_(i) is linked to. (For example,                how many of my friends are friends with each other?)                This sequence is in descending order of the clustering                coefficient.

        -   c. Betweenness Centrality of node i:

$B_{i} = {\sum\limits_{s \neq i \neq t}\frac{\sigma_{st}(i)}{\sigma_{st}}}$

-   -   -   -   where σ_(st) is the total number of shortest paths from                nodes s and t and σ_(st)(i) is the subset of σ_(st) that                pass through node i. (This is the extent to which node i                acts as a key bridge between other nodes). This sequence                is in descending order of betweenness centrality.

        -   d. Closeness Centrality of node i:

$C_{i} = \frac{1}{\sum\limits_{y}{d\left( {y,i} \right)}}$

-   -   -   -   where d(y,i) is the distance (number of network steps)                between nodes i and y. (So, the smaller the number of                steps, the more ‘central’ the node is to the overall                network.)

        -   e. Eigenvector Centrality of node i:

${EV}_{i} = {{\frac{1}{\lambda}{\sum\limits_{t \in {M{(i)}}}{EV}_{t}}} = {\frac{1}{\lambda}{\sum\limits_{t \in G}{a_{i,t}{EV}_{t}}}}}$

-   -   -   -   where M(i) is the set of nodes connected to node i and λ                is a constant (an eigenvalue) identified via a matrix                computation. In simpler terms, the eigenvector                centrality of node i is the sum of the centrality values                of each node it is linked to—implying that more                “important” nodes are more likely to be connected to                other nodes that are “important” (“important” in this                case meaning highly connected.) In the above, a_(i,t)=1                if node i is connected to node t and a_(i,t)=0 if it is                not. G is the entire possible set of nodes; M(i) is the                subset of nodes connected to node i, so

$\frac{1}{\lambda}{\sum\limits_{t \in {M{(i)}}}{EV}_{t}}$

-   -   -   -   is the same as

${\frac{1}{\lambda}{\sum\limits_{t \in G}{a_{i,t}{EV}_{t}}}},$

-   -   -   -   just stated differently. In the latter equation, a_(i,t)                is needed, because the equation is not restricted to                considering nodes connected to i. In summary, these two                summations are the same. Eigenvector centrality is                computed for each node and ranges from largest to                smallest.

    -   (5) For each sequence SEQ listed in step 4:        -   f. Set STEPS_(SEQ)=0        -   g. For each node in SEQ:            -   i. Add node back to network and restore each of its                connections            -   ii. Calculate SCF=FF/TF, where FF=total number of                connected nodes in current network            -   iii. Stop when SCF=1            -   iv. Increment STEPS_(SEQ) by 1

    -   (6) Holding all else constant, the optimal recovery strategy is        that SEQ which achieves SCF=1 (or another desired value between        0 and 1) with the smallest STEPS_(SEQ).

The efficiency of each recovery sequence can also be measured bycomputing its corresponding impact area (IA), which is defined as thearea between the recovery curve and the y-axis representing SCF (seeFIG. 2 or 6). Hence, a smaller IA indicates a more efficient recoverystrategy.

FIG. 5 illustrates a simplified example of a disruption process followedby a recovery process according to the present system and method. Twonodes X and Y are selected randomly for removal at time T=1 and T=2,respectively.

(1) The SCF=1 at step T=0 (pre-hazard). Node X (black in subpanel (1) onthe left) is selected for removal at step T=1.

(2) Removal of node X results in reduction of the size of the GiantComponent (GC), which sets SCF=0.5. Dashed nodes (edges) are the nodes(edges) that get detached from the GC and hence incapacitated. Node Y(black in subpanel (2)) is selected for removal at step T=2 (f=⅙,meaning one out of the six nodes is targeted for removal).

(3) The GC ceases to exist after the removal of node Y. All nodes areshown in dashed lines in subpanel (3). SCF=0.

To highlight the asymmetric nature of the recovery process, nodes arerestored to their full functionality in the same order these wereremoved (i.e. node X followed by node Y) from the network.

(4) Node X (brick pattern in subpanel (4) on the right) is selected forrestoration to full functionality in the first step of the recoveryprocess.

(5) This results in the recovery of the node X to full functionality(f′=⅙, meaning one out of the six nodes is fully functional). As aresult, three nodes directly connected to X gain at least one edge andthe GC grows, making SCF=0.67. Then, node Y (brick pattern in subpanel5) is selected for recovery in step (6).

(6) Recovery of node Y to its full functionality results in restorationof the SCF of the network to 1 as shown in subpanel (6).

The method and system for recovering a network from a state ofdisruption to a state of partial or complete functionality as describedherein can be implemented as or can include a computing device thatincludes a combination of hardware, software, and firmware that allowsthe computing device to run an applications layer or otherwise performvarious processing tasks. Computing devices can include withoutlimitation personal computers, work stations, servers, laptop computers,tablet computers, mobile devices, hand-held devices, wireless devices,smartphones, wearable devices, embedded devices, microprocessor-baseddevices, microcontroller-based devices, programmable consumerelectronics, mini-computers, main frame computers, and the like.

The computing device can include a basic input/output system (BIOS) andan operating system as software to manage hardware components,coordinate the interface between hardware and software, and manage basicoperations such as start up. The computing device can include one ormore processors and memory that cooperate with the operating system toprovide basic functionality for the computing device. The operatingsystem provides support functionality for the applications layer andother processing tasks. The computing device can include a system bus orother bus (such as memory bus, local bus, peripheral bus, and the like)for providing communication between the various hardware, software, andfirmware components and with any external devices. Any type ofarchitecture or infrastructure that allows the components to communicateand interact with each other can be used.

Processing tasks can be carried out by one or more processors. Varioustypes of processing technology can be used, including a single processoror multiple processors, a central processing unit (CPU), multicoreprocessors, parallel processors, or distributed processors. Additionalspecialized processing resources such as graphics (e.g., a graphicsprocessing unit or GPU), video, multimedia, or mathematical processingcapabilities can be provided to perform certain processing tasks.Processing tasks can be implemented with computer-executableinstructions, such as application programs or other program modules,executed by the computing device. Application programs and programmodules can include routines, subroutines, programs, drivers, objects,components, data structures, and the like that perform particular tasksor operate on data.

The computing device includes memory or storage, which can be accessedby the system bus or in any other manner. Memory can store controllogic, instructions, and/or data. Memory can include transitory memory,such as cache memory, random access memory (RAM), static random accessmemory (SRAM), main memory, dynamic random access memory (DRAM), andmemristor memory cells. Memory can include storage for firmware ormicrocode, such as programmable read only memory (PROM) and erasableprogrammable read only memory (EPROM). Memory can include non-transitoryor nonvolatile or persistent memory such as read only memory (ROM), harddisk drives, optical storage devices, compact disc drives, flash drives,floppy disk drives, magnetic tape drives, memory chips, and memristormemory cells. Non-transitory memory can be provided on a removablestorage device. A computer-readable medium can include any physicalmedium that is capable of encoding instructions and/or storing data thatcan be subsequently used by a processor to implement embodiments of themethod and system described herein. Physical media can include floppydiscs, optical discs, CDs, mini-CDs, DVDs, HD-DVDs, Blu-ray discs, harddrives, tape drives, flash memory, or memory chips. Any other type oftangible, non-transitory storage that can provide instructions and/ordata to a processor can be used in these embodiments.

The computing device can include one or more input/output interfaces forconnecting input and output devices to various other components of thecomputing device. Input and output devices can include, withoutlimitation, keyboards, mice, joysticks, microphones, displays, monitors,scanners, speakers, and printers. Interfaces can include universalserial bus (USB) ports, serial ports, parallel ports, game ports, andthe like.

The backend and front end can be implemented on a single computingdevice or can be implemented on distributed computing devices incommunication over any suitable communication network. The computingdevice or devices can access a network over a network connection thatprovides the computing device(s) with telecommunications capabilities.Network connection enables the computing device(s) to communicate andinteract with any combination of remote devices, remote networks, andremote entities via a communications link. The communications link canbe any type of communication link, including without limitation a wiredor wireless link. For example, the network connection can allow thecomputing device to communicate with remote devices over a network,which can be a wired and/or a wireless network, and which can includeany combination of intranet, local area networks (LANs), enterprise-widenetworks, medium area networks, wide area networks (WANs), the Internet,cellular networks, and the like. Control logic and/or data can betransmitted to and from the computing device via the network connection.The network connection can include a modem, a network interface (such asan Ethernet card), a communication port, a PCMCIA slot and card, or thelike to enable transmission of and receipt of data via thecommunications link.

The computing device can include a browser and a display that allow auser to browse and view pages or other content served by a web serverover the communications link. A web server, server, and database can belocated at the same or at different locations and can be part of thesame computing device, different computing devices, or distributedacross a network. A data center can be located at a remote location andaccessed by the computing device over a network.

The computer system can include architecture distributed over one ormore networks, such as, for example, a cloud computing architecture.Cloud computing includes without limitation distributed networkarchitectures for providing, for example, software as a service (SaaS),infrastructure as a service (IaaS), platform as a service (PaaS),network as a service (NaaS), data as a service (DaaS), database as aservice (DBaaS), backend as a service (BaaS), test environment as aservice (TEaaS), API as a service (APIaaS), and integration platform asa service (IPaaS).

Example

FIGS. 6-8 illustrate a disruption to and then recovery of a networkusing the Indian Railway Network (IRN) as an example. FIG. 7 is anillustration of the lifeline network at issue in this example. FIG. 6shows disruptions (decreasing curves on the left) and then recoverysequences (increasing lines on the right). Thus, the right panelillustrates the present recovery system and method. Each line shows theincrease in the SCF under different node prioritization sequences. Eachsequence was generated by a different strategy. The gray envelopecaptures 1,000 random strategies as a baseline—if nodes are restored ina completely random order, how fast will SCF increase? The otherdifferent styled lines are recovery trajectories based on recoverysequences that are generated by specific metrics: betweenness centrality(solid line), degree (dashed-dotted line), and randomly (dashed line andgrey envelope), as described above. For instance, the dashed-dotted lineis where nodes (stations in this case) are recovered in descending orderof how many links each node has—the more links a node has, the earlierit is recovered. In this particular case, betweenness centrality turnsout to be the best recovery sequence. Thus, the recovery method providesfor the generation of different recovery sequences to see which onesrestore the lifeline network fastest/most efficiently.

The IRN network database was constructed using publicly available data(from open source databases of express and local passenger trains inIndia (at indianrail.gov.in, indianrailways.in) and an e-ticket bookingcompany (at ixigo.com)) that was cleaned and appropriately formatted.The IRN was modeled as an origin-destination network. Stations with atleast one originating or terminating train, comprising 752 out of atotal of 809 stations, were considered. Thus, 752 stations make up thegiant component (the largest connected group of stations). Accordingly,total functionality TF=752.

Each station's degree, or connectivity, is measured by the number ofconnections it has with other stations. Each station's strength ismeasured by its total traffic volume in terms of the total number oftrains that originate or terminate at that station. Strength is definedthis way with the hypothesis that traffic volume can be a useful metricfor understanding failure and/or for prioritizing stations duringrecovery. Two stations i and j are considered to be connected by an edgeif there exists a train between the pair of stations such that a trainoriginating at i terminates at j. Elements of the adjacency matrix{a_(ij)} are 1 if the train originating from station i terminates atstation j and 0 otherwise. The weight of an edge is calculated as thenumber of trains running between a pair of stations in either direction.Thus, any element of the weighted adjacency matrix {wij} is the numberof trains originating from station i and terminating at station j. Theconnections were almost all bidirectional; specifically, the numbers oftrains connecting pairs of stations in one direction were different fromthe other directions in less than 250 out of the 654,481 possible cases(less than 0.04% of cases). The traffic flow matrix could therefore bemade symmetric without much distortion of the network by selecting thelarger non-zero value per station pair. Hence, the IRN is analyzed as anundirected weighted network. To understand the structure of IRN, thedegree and strength distribution of the stations are calculated. Thecumulative degree distribution P(k>K) gives the probability that astation has more than K connections to other stations and is defined as:

P(k>K)=1−Σ_(k=k) _(min) ^(K) p(k)

where p(k) is number of stations having degree k divided by total numberof stations and k_(min) is the minimum degree found over all nodes inthe network. Similarly, cumulative distribution of strength P(S>s) givesthe probability that a station has more than S originating (orterminating) trains, i.e., traffic volume. The cumulative degree andstrength distributions follow truncated power law models. Most stationshave a small number of connections, with the exception of several hubsthat are generally related to major metropolitan areas as well asgeospatially isolated from each other.

The modularity-based Louvain community detection algorithm is used tocharacterize the topology of the IRN. The weighted adjacency matrixdefined earlier is used as the input for the community detection. Thetopology of the network can provide interpretation for the IRN'srobustness to and recovery from different types and geographical originsof hazards.

Results indicate that recovery strategies do not necessarily follow thesequence in which the nodes were damaged during network collapse. FIG. 6translates the formerly conceptual hazard response curves intoquantitative terms, with the IRN functionality degrading owing to eithertargeted station removal or random failures (e.g., potentially fromrandom but typical service disruptions, shown by dashed line on leftside panel). The targeted station removals may be caused by targetedattacks that prioritize the stations to be taken down by connectivity ordegree (solid line on left side panel), or by traffic volume or strength(dotted line on left side panel). Network robustness computationsapplied to the IRN suggest that while random failures would need toeliminate 95% of the stations for near complete loss of functionality,the corresponding numbers are 25% for targeted attacks by number ofconnections and 23% for targeted attacks by traffic volume.

In the right panel of FIG. 6, recovery strategies are compared for thecase where the IRN starts at a SCF=0, i.e., completely unconnected anddysfunctional. The optimum recovery strategy can be defined in terms ofresources required and/or time taken for partial or full recovery offunctionality. The metric SCF is used as a proxy for those resources ortime. Three types of recovery alternatives are evaluated. First, N=1000random sequences serves as a baseline for comparison (dashed line onright panel). The second set of strategies, perhaps the most immediatelyintuitive, is based on station attributes including connectivity andtraffic volume. For simplicity, one strategy of the second set, numberof connections, is illustrated in FIG. 6 (dash-dot line on right panel).The third set of strategies is based on network centrality measures,such as eigenvector (by average importance of connected stations),closeness (by average proximity to other stations, in a networkconnectivity but not necessarily a geographic sense), and betweenness(by the average number of times any passenger traveling betweenorigin-destination station pairs needs to go through the station underconsideration). For simplicity, one strategy of the third set, stationbetweenness, is illustrated in FIG. 6 (solid line on right panel).

As noted above, the efficiency of each recovery sequence can be measuredby computing the impact area IA, the area between the recovery curve andthe y-axis representing SCF. In this case, IRN recovery is mostefficient at most stages of partial or full recovery when betweennesscentrality is chosen for generating a recovery sequence. On average,random recovery sequences require resources (calculated as the impactarea, averaged over the N=1000 random sequences) in excess of 250%compared with the betweenness centrality-based sequence. Recovery basedon the connectivity (degree) sequence requires resources in excess of67% compared to betweenness centrality. The interpretation for theperformance of betweenness centrality in this case is discussed furtherbelow.

The present method and system can also be used for communities within anetwork. For example, the IRN has a number of relatively independentcommunities. The two largest communities were considered separately andanalyzed. For full recovery of the IRN, betweenness centrality wasdetermined to be the most efficient strategy. However, at some stages ofpartial recovery, the most efficient metric may not be the same as forthe full network. For example, for a community spanning South India,closeness centrality generates a particularly suboptimal sequence. Thisis a likely consequence of the fact that there are many geospatiallyproximal stations in this region that are not connected to many others.In both communities analyzed (South and North India), betweennesscentrality ultimately emerges as the best metric for prioritizingstations for full recovery of the IRN or the vast majority of itsfunctionality. The results suggest that the framework generalizes butthat the choice of the most appropriate recovery strategy may depend onthe network, the community, or the desired state of recovery (i.e.,level of desired SCF).

In some cases, the network recovery process may not need to begin from astate of complete disrepair (i.e., at SCF=0). This motivates testing theutility of the framework on exemplary set of realistic hazards that onlypartially incapacitate the IRN.

Accordingly, the recovery portion of the framework subject to threespecific hazards was also examined. First, a simulation inspired by the2004 Indian Ocean tsunami removes 9% of stations on the southeasternIndian coast. Second, a scenario was simulated based on a cascade fromthe power grid, similar to the fallout from the historically massive2012 blackout. Third, a hypothetical cyber or cyber-physical attackscenario was simulated, where the stations are perhaps maliciouslytargeted based on traffic volume the network structure is fracturedsignificantly. Cyber-physical terror attacks may be region-specific, butthe possibility of coordinated attacks exists, especially for cyber. Thepost hazard SCF values are 0.903, 0.852, and 0.890 (679, 641, and 669nodes remaining in the giant component) respectively for the threehazards, and recovery begins from these starting points.

An ensemble of N=1000 members of random sequences are used in each caseas a baseline. All metrics lead to recovery sequences that are almostalways more effective than the random sequences. It is less clear whichmetrics lead to the most effective recovery sequences in general. In allthree cases, a choice of betweenness centrality leads to totalfunctionality (SCF=1) earliest, although at earlier stages other metricsare at times preferable.

An example using data from the IRN to illustrate a quantifiable gain inrevenue from several recovery sequences is described with reference toFIG. 8. This figure illustrates the percentage recovery of dailyrevenues generated by the IRN for several recovery sequences. The shadedbounds designate 1000 random recovery sequences. Also shown arestrength, betweenness centrality, and closeness centrality. Thehorizontal axis is time or recovery steps, and the vertical axis assumesthat each “trip,” a train going from a node to a node, generates$10,000.00 in revenue per day, based on actual data from the IRN. Itwill be appreciated that the actual value is not significant, becausethe analysis can determine percentages. At full functionality, the IRNgenerates 100% of the revenue that it should. Then, assume the networkis fully disrupted and recovered using the various recovery sequences.The number of trips (from node to node) is measured at each state ofrecovery and divided by the number of trips on the entire IRN at fullfunctionality (hence, the number is always between 0 and 1).

This study presents a complex network-based unified framework that goesbeyond fragility characterization and conceptual resilience curves tooffer data-driven, quantitative insights for decision-making before,during and after hazards to enable preparedness, relief and recovery.While the fragility characterization may be considered an adaptation ofexisting network science methods, recovery curves are new and cangeneralize to other applications. The framework developed here allowsfor generation and performance comparison of multiple node recoverysequences, allowing for the possibility that different networks shouldbe recovered according to sequences generated from different metrics.The recovery differs from a straightforward application of percolationtheory in that the sequence of node recovery does not necessarily followthe sequence in which they were damaged during network collapse. Therecovery of a node accompanies the recovery of the links and hencetraffic flow to directly connected nodes.

As used herein, “consisting essentially of” allows the inclusion ofmaterials or steps that do not materially affect the basic and novelcharacteristics of the claim. Any recitation herein of the term“comprising,” particularly in a description of components of acomposition or in a description of elements of a device, can beexchanged with “consisting essentially of” or “consisting of.”

It will be appreciated that the various features of the embodimentsdescribed herein can be combined in a variety of ways. For example, afeature described in conjunction with one embodiment may be included inanother embodiment even if not explicitly described in conjunction withthat embodiment.

The present invention has been described in conjunction with certainpreferred embodiments. It is to be understood that the invention is notlimited to the exact details of construction, operation, exact materialsor embodiments shown and described, and that various modifications,substitutions of equivalents, alterations to the compositions, and otherchanges to the embodiments disclosed herein will be apparent to one ofskill in the art.

What is claimed is:
 1. A method for providing a recovery sequence for anetwork from a state of disruption to a state of partial or completefunctionality, the network comprising a plurality of nodesinterconnected by links, the network subject to disruption that removesfrom the network one or more nodes, one or more links, or a combinationof one or more nodes and one or more links, wherein a disrupted node isa node through which traffic cannot flow and a functional node is a nodethrough which traffic can flow, the method comprising: providing abackend computing device comprising one or more processors and memory,and a user interface in communication with the backend computing device;storing, in a database in the memory, data comprising identities of thenodes and the links of the network, attributes of the nodes, andattributes of the links; receiving user preference data from a user atthe user interface, the user preference data including a state ofdesired functionality, and one or more of a type of hazard, severity ofhazard, location of hazard, resilience budget, and cost of node or linkrepair; receiving, at the backend computing device, an identification ofa plurality of the nodes as disrupted nodes; determining, by ascientific engine comprising instructions stored in the memory forexecution by the one or more processors, a priority recovery sequence bywhich disrupted nodes are to be restored to the state of desiredfunctionality; and providing to the user interface a priority recoverysequence to restore the network to the desired state of functionality.2. The method of claim 1, wherein storing data comprises one or more of:(a) populating a network data object with the data comprising theidentities of the nodes and the links of the network, the attributes ofthe nodes, and the attributes of the links, and pushing the network dataobject to the database stored in the memory; (b) augmenting oroverriding the data in the network data object in the database with afurther data input by a user at the user interface; and (c) queryingnode and link data to refresh the node and link data, and pushing anupdated network data object to the database.
 3. The method of claim 2,wherein step (c) comprises querying the node and link data on a periodicschedule.
 4. The method of claim 1, wherein identifying the nodes asdisrupted nodes comprises receiving an input from an external computingdevice, from sensors located at the nodes, or from the user interfacecomprising identities of disrupted nodes or links.
 5. The method ofclaim 1, further comprising: receiving from a sensor located at adisrupted node data indicating that the disrupted node has been restoredto functionality; updating, by the scientific engine, the priorityrecovery sequence; and providing the updated priority recovery sequenceto the user interface.
 6. The method of claim 1, wherein providing thepriority recovery sequence to the user interface comprises transmittinga graphical display to the user interface comprising a graphillustrating a fraction of disrupted nodes vs. a state of criticalfunctionality for one or a plurality of recovery sequences.
 7. Themethod of claim 6, further comprising transmitting a graphical displayto the user interface comprising a graph illustrating a fraction ofdisrupted nodes vs. a state of critical functionality for a variety ofhazard scenarios.
 8. The method of claim 1, further comprising providingto the user interface one or more metrics comprising financial savings,prevented down time of the network, prevented temporal businessinterruption, prevented socioeconomic damage, prevented disease spread,mitigated transportation losses in terms of traffic volume not delayed,prevented downtime in power supply from a blackout or brownout,prevented Internet downtime, or prevented natural ecosystem losses thatresult from alternative proposed recovery sequences.
 9. The method ofclaim 1, wherein the user interface is provided on an external computingdevice.
 10. The method of claim 1, wherein the step of determining apriority recovery sequence comprises: determining, by the scientificengine, a giant component of the nodes, the giant component comprising alargest connected set of nodes; and determining, by the scientificengine, an initial value of a state of critical functionality (SCF), theSCF ranging from 0 to 1 and comprising a fragmented functionality (FF)divided by a total functionality (TF), wherein: FF is a number offunctional nodes in the giant component at a determined time, and TF isa total number of nodes in the giant component when the network is fullyfunctional; and simulating, by the scientific engine, restoration of thedisrupted nodes one by one to functionality until a desired value of SCFis obtained.
 11. The method of claim 10, wherein simulating restorationof a disrupted node comprises adding the disrupted node and theconnections of the disrupted node to its neighboring nodes back to thenetwork.
 12. The method of claim 10, wherein determining a priorityrecovery sequence comprises: (a) determining a first SCF value afterdisruption; (b) simulating restoration of one of the disrupted nodes tofull functionality; (c) calculating a number of functional nodes in thegiant component; (d) determining a further SCF value; and (e) repeatingsteps (b) through (d) until a desired SCF value is reached.
 13. Themethod of claim 10, further comprising weighting the attributes of thenodes and the attributes of the links, and determining the desired SCFvalue using the weighted attributes.
 14. The method of claim 1, whereinthe step of receiving an input of a disruption further comprisesidentifying links between any disrupted node and a neighboring node. 15.The method of claim 1, wherein determining a priority recovery sequencecomprises determining multiple recovery sequences and comparing themultiple recovery sequences to determine the priority recovery sequence.16. The method of claim 15, wherein the determined recovery sequencecomprises one or more of: (a) a sequence in which a desired SCF valuecan be achieved in a fastest time. (b) a sequence in which a desired SCFvalue can be achieved with a fewest number of steps. (c) placing thedisrupted nodes in order by degree, wherein degree comprises a number oflinks to a node, and simulating restoration of the disrupted nodes tofunctionality, in order from largest degree to smallest degree, until adesired value of SCF is obtained; (d) placing the disrupted nodes inorder by clustering coefficient, wherein the clustering coefficient isproportional to a number of links to nodes to which a disrupted node islinked, and simulating restoration of the disrupted nodes tofunctionality, in order from largest clustering coefficient to smallestclustering coefficient, until a desired value of SCF is obtained; (e)placing the disrupted nodes in order of betweenness centrality, whereinthe betweenness centrality is a measure of how frequent a disrupted nodeis a bridge between otherwise disconnected groups of intra-linked nodes,and simulating restoration of the disrupted nodes to functionality, inorder from largest betweenness centrality to smallest betweennesscentrality, until a desired value of SCF is obtained; (f) placing thedisrupted nodes in order of closeness centrality, wherein the closenesscentrality is an inverse of a summation of a number of network stepsbetween a node and other nodes, and simulating restoration of thedisrupted nodes to functionality, in order from smallest closenesscentrality to largest closeness centrality, until a desired value of SCFis obtained; (g) placing the disrupted nodes in order of eigenvectorcentrality, wherein the eigenvector centrality is a sum of thecentrality values of each node that is linked to a disrupted node, andsimulating restoration of the disrupted nodes to functionality, in orderfrom largest eigenvector centrality to smallest eigenvector centrality,until a desired value of SCF is obtained; and (h) placing the disruptednodes in a random order, and simulating restoration of the disruptednodes to functionality in the random order, until a desired value of SCFis obtained.
 17. The method of claim 1, wherein node attributes and linkattributes include one or more of: (a) strength measured as a volume oforiginations or terminations at a node or measured as a number ofobjects originating or terminating at the node; (b) strength measured asa volume of traffic along a link; (c) financial value associated with anode or a link in terms of a cost of repairing, recovering, or replacingthe node, or a cost of repairing, recovering or replacing the link; (d)financial value associated with a node or a link in terms of businessinterruption costs related to the node or the link being out of service.(e) geospatial information, including one or more of latitude,longitude, and height above sea level. (f) a quantifiable social cost orvariable associated with a node, including one or more of a povertyrate, an employment rate, a quantification of access to social services,and a quantification of access to alternative transportation. (g) civilinfrastructure data associated with a node or a link. (h) naturalenvironment data associated with a node or a link.
 18. A method ofrecovering a network from a state of disruption to a state of partial orcomplete functionality, the network comprising a plurality of nodesinterconnected by links, the network subject to disruption that removesfrom the network one or more nodes, one or more links, or a combinationof one or more nodes and one or more links, wherein a disrupted nodecomprises a node through which traffic cannot flow and a functional nodecomprises a node through which traffic can flow, the method comprising:performing the method of claim 1; and implementing the recoverysequence, comprising restoring at least a first disrupted node or afirst disrupted link to functionality according to the recoverysequence.
 19. The method of claim 18, wherein the network is selectedfrom the group consisting of a transportation network, an energynetwork, a telecommunication network, an Internet network, a watersupply network, a wastewater network, a financial network, a socialnetwork, a climate and weather network, a geopolitical network, anecological network, or a disease network.
 20. The method of claim 18,wherein the network comprises a telecommunication network or an Internetnetwork.